Anti-natal diagnosis of Syntelencephaly: Midline interhemispheric variant of holoprosencephaly

A 25-year-old primi gravida came for routine second trimester ante-natal sonography. Uneventful pregnancy with no significant family history or past history. Sonographic evaluation was followed by termination of the five month old foetus. MRI confirmation of abortus confirmed diagnosis of syntelencephaly.

Ultrasonography (USG) revealed evidence of fusion of the posterior frontal and anterior parietal lobes across the midline. Fusion of the frontal horns and body of both the lateral ventricles is seen with nonvisualization of the cavum septum pellucidum. The choroid plexuses of the lateral ventricles are seen touching each other. Both the thalami are well seenand separate. Fetal facial structures are normal. MRI revealed well seperated anterior frontal, posterior parietal and occipital lobes. Fusion of the posterior frontal and parietal lobes is seen. Absent septum pellucidum with fusion of bilateral lateral ventriclesis seen, confirming ultrasonographic diagnosis of midline variant of holoprosencephaly [syntelencephaly].

Mutations in the gene encoding the Sonic Hedgehog protein, which is involved in the development of the central nervous system (CNS), can cause holoprosencephaly [1]. Posterior frontal lobe and the parietal lobe are not properly separated, but the rostro basal fore brain properly separates. Clinical presentations can vary, with mental defect, spasticity, dystonia and oromotor dysfunction or global developmental delay being common. Poor prognosis is offered, hence early ante-natal diagnosis gives the option of timely termination [2]. Anterior and posterior hemispheres are separated by falx and inter hemispheric fissure, but their midsections are fused across midline. In contrast to classic holoprosencephaly, ventral portions of the basal fore brain are largely spared [3]. Imaging guides modern medicine to allow patients with brain malformations to survive infancy, often until adulthood. Diagnosing and prognosticating is possible with various modalities [4]. Implications of diagnosis allows proper counseling of caregivers and future needs of the child. Our case was diagnosed early in utero at 20 weeks of gestation. Early ante-natal diagnosis allows parents to choose if they want to continue the pregnancy, considering social and economic implications with quality of life.